1. Field of the Invention
The present invention relates to a heat-shrinkable biaxially drawn polyamide film and a process for the preparation thereof. More particularly, it relates to a heat-shrinkable biaxially drawn polyamide film suitable for shrink-packaging processed meat products, such as ham and sausage, daily necessities, and groceries.
2. Description of the Related Art
Heat-shrinkable polyamide films formed from a nylon 6 homopolymer by the tubular film simultaneous biaxial drawing method are in practicle use, but these films have an unsatisfactory thickness accuracy and production rate or productivity.
Furthermore, films prepared from a starting material composed mainly of a polycondensation polymer of metaxylenediamine and an aliphatic carboxylic acid by the tenter type sequential biaxial drawing method are in practicle use. However, since a special starting material must be used, the manufacturing cost is high.
Other processes are proposed in Japanese Unexamined Patent Publications No. 56-49,226, No. 57-170,720, and NO. 58-78,728. However, these processes have a problem in that a special starting material must be used.